Small-Scale Water Current Turbines for River Applications

Small-scale Water Current Turbines for River Applications

January 2010 Kari Sørnes About ZERO Zero Emission Resource Organization is an environmental organization dedicated to reducing climate change by demonstrating and gaining acceptance for zero emission energy solutions. We believe a zero emission solution exists for all energy use. Our mission is to work consistently for these solutions.

Contact us at: ZERO – Zero Emission Resoruce Organisation Maridalsveien 10 0178 Oslo www.zero.no [email protected] Table Of Contents

Summary��4 1 Introduction��5 2.1 Conversion and Operation��6 2.1.1 Conversion Schemes��6 2 The Technology of Water Current Turbines��6 2.1.2 Augmentation��7 2.1.3 The Flow of the River and Siting Considerations�� 7 3 Companies and technologies��8 3.2 Companies and concepts��9 3.2.1 Thropton Energy Services (UK)��9 3.2.2 Alternative Hydro Solutions Ltd. (Canada)�� 10 3.2.3 Energy Alliance (Russia)��11 3.2.4 New Energy Corporation Inc. (Canada)�� 12 3.2.5 Seabell International Co., Ltd. (Japan) �� 13 3.2.6 Lucid Energy Technologies (US)�� 14 3.2.7 Tidal Energy Pty. Ltd. (Australia)��15 3.2.8 Eclectic Energy Ltd. (UK)�� 16 4 Research and experiences��17 5 Discussion�� 18 6 References�� 19

ZERO - Small-scale Water Current Turbines for River Applications Summary

The purpose of this report is to get an overview of the existing technology of water current turbines with a unit power output of about 0.5-5 kW.

Water current turbines, or hydrokinetic turbines, produce electricity directly from the flowing water in a river or a stream. No dam or artificial head is needed to produce the small-scale power output. Several of the devices mentioned in the report may have application in tidal waters, ocean currents and manmade channels, but the scope of this report is limited to applications in free-flowing rivers.

Reviews of the most common existing turbine technologies are outlined. The two most common small- scale hydrokinetic turbine concepts are axial flow turbine and cross-flow turbine. Of importance for the power production is whether the turbine is ducted or not. Where to place the turbine must also be well considered.

The report summarizes the commercial market which exists in this field and considers some previous experiences in rural areas. Several companies from different parts of the world are presented with their concept. To find the companies which are established and emerging within this field, a web-based search is performed. Previous reports dealing with this subject are also reviewed.

Small-scale hydro power from water current turbines is considered to be reliable and ecologically friendly. Because of the low cost and the longevity of micro hydro, developing countries may manufacture and implement the technology to help supply the needed electricity to small communities in remote areas. Discussions on performance analysis and modelling issues are beyond the scope of this work.

ZERO - Small-scale Water Current Turbines for River Applications 1 Introduction

The natural power of a running river or a stream has For the scope of this report the focus was on appli- been of interest for electricity production for many cations in free-flowing rivers, although several of the years. The technology of small-scale hydro power is devices may have applications in tidal waters, ocean diverse, and different concepts have been developed currents and man-made channels. and tried out. This report will focus on water current turbines with a unit power output of about 0.5-5 kW. Short reviews of some of the existing turbine tech- These turbines are supposed to be used for domestic nologies are outlined. The paper will also look at the electricity applications such as lighting, battery char- commercial market in this field and consider some ging, or for the use of a small fridge. The units are experiences already made in rural areas in different small, cheap and often owned, installed, and used by parts of the world. In order to find the existing tech- a single family. nologies and companies with viable concepts, a web- based search is accomplished. Earlier written reports Water current turbines, also called hydro kinetic or are also reviewed. in-stream turbines, have received a growing interest in many parts of the world. Two main areas where Discussions on performance analysis and modelling hydrokinetic devices can be used for power genera- issues are beyond the scope of this work. tion purposes are tidal currents and river streams. This report will focus on water current turbines for This report have been made with financial support river applications. These turbines generate power from Norad - Norwegian Agency for Development from the kinetic energy of a flowing stream of water Cooperation. without the use of a dam or a barrage. Water current turbines can be installed in any flow with a velocity greater than 0.5 m/s [1]. Because of low investment costs and maintenance fees, this technology is cost effective in comparison to other technologies. The continuous supply of electrical energy is also an advantage in comparison to solar power or other small- scale renewable technologies. This kind of small-scale hydropower is considered environmentally friendly, meaning that the water passing through the generator is directed back into the stream with relatively small impact on the surrounding ecology.

Small-scale water current turbines can be a solution for power supply in remote areas. Because of the low cost and durability of this kind of hydro power, developing countries can manufacture and implement the technology to supply the needed electricity to small communities and villages [2].

There are different kinds of small-scale hydropower. The term “pico hydropower” is said to be water power up to 5kW and is a smaller version of the more established term; micro hydropower. Pico hydropower is usually used when we think of hydropower on a regu- lar basis, where the power is made by falling water and an artificial water-head. The report will not consider this type of hydropower. The report will mainly focus on kinetic “in-stream” hydro turbines. These turbines produce electricity from the free-flowing water in a river or stream and do not rely upon a water-head to produce electricity.

ZERO - Small-scale Water Current Turbines for River Applications 2 The Technology of Water Current Turbines

Water current turbines, or hydrokinetic turbines, produce electricity directly from the flowing water in a river or a stream. The energy flux of the water stream is dependent on the density, cross-sectional area and velocity cubed (eq. 2.0.1). A number of different concepts have been developed to utilise this power throughout the world. While turbine systems are considered prime choices for such conversion, other non-turbine possibilities are also being pursued with interest. At present, the non-turbine systems are mostly at the prototype stage. [3] This report will thus exclusively focus on turbine systems.

(2.0.1) P = Power (watt) ρ = Water density (kg/m3) Figure 2.1.1.2: Cross-folw turbines [4]

Ck= Power coefficient A = Turbine area ( m2) lel to the incoming water stream. This is illustrated V = Velocity of water (m/s) in figure 2.1.1.1. The inclined axis turbines (a) have mostly been studied for small river energy converters. 2.1 Conversion and Operation The horizontal axis (b, c and d) turbines are common When considering the possible use of a water cur- in tidal energy converters and are very similar to mo- rent turbine on river applications, several issues are dern day wind turbines from design and structural of concern with regards to the power production per- point of view. [4] formance. The next chapter will give a general introduction to the technology of this field. The cross-flow concept on the other hand, has a -ro tational axis of rotor which is parallel to the water 2.1.1 Conversion Schemes surface, but orthogonal to the incoming water stream Several hydrokinetic conversion concepts have been [3]. The advantage of cross-flow turbines is that they developed through the years. The two most com- can rotate unidirectional even with bi-directional flu- mon small-scale hydrokinetic turbine concepts are id flow. They can be divided into two groups: axial flow turbine and cross-flow turbine. The axial concept has a rotational axis of rotor which is paral- 1. Vertical axis, with an axis vertical to the water plane. Different types are illustrated in figure 2.1.1.2. In the vertical axis domain, the use of H-Darrieus or Squirrel Cage Darrieus is rather common. Instances of Darrieus turbines being used to produce hydropower are nearly non-existent. The Gorlov turbine is another member of the vertical axis family, where the blades are of helical structure. Savonious turbines are “drag type” devices, which may consist of straight or skewed blades. The disadvantages associated with vertical axis turbines are: low starting torque, torque ripple, and lower efficiency. [4] These turbines may not be self-starting and therefore some kind of exter- nal starting mechanisms need to be adopted.

2. In-plane axis, with an axis on the horizontal plane of the water surface. These are better known as floating waterwheels. The in-plane turbines are mainly drag based devices and said to be less efficient than Figure 2.1.1.1: Axial-flow (horizontal) turbines [4] their lift based counterparts. The large amount of ma-

ZERO - Small-scale Water Current Turbines for River Applications terial usage can be another problem for such turbines. 2.1.3 The Flow of the River and Siting [4] Considerations Axial flow turbines are self-starting and the issue of The best performance and the highest power produc- start up is not significant. However, they come with tion is made by a smooth linear flow of water at high a price of higher system cost owing to the use of sub- velocity [5]. The flow characteristic of a river stream merged generator or gearing equipment. Vertical axis has a stochastic variation, both seasonal and daily, and turbines, especially the H-Darrieus types with two or where to put the water current turbine must therefore three blades are reasonably efficient and simpler in be well considered. A positive aspect of the flow of design, but not self-starting. Mechanisms for starting rivers is that it is unidirectional, which eliminates the these rotors from a stalled state could be devised from requirement for rotor yawing. mechanical or electromechanical perspectives. [15] For a hydrokinetic converter, the level of power output is directly related to flow velocity. The volumetric 2.1.2 Augmentation flow information may be available for the location, Whether the turbine is ducted or not is of great im- but the water velocity varies from one potential site to portance for the performance of the turbine. Ducts the other depending on the cross-sectional area. [3] or diffusers are engineered structures that elevate The placement of a hydrokinetic device, in relation the energy density of a water stream as observed by to a channel cross-section, is a very significant com- a hydrokinetic converter [3]. The duct, or augmen- ponent for two basic reasons. First of all, the energy tation channel, increases the possible total power flux in the surface of a stream is higher than that of capture significantly. In addition, it may help regulate the stream on the bottom. In addition, this quantity the speed of the rotor and reduce problems caused by takes diverse values depending on the distance from low-speed drive train design. A consideration for the- the shore. In a smooth channel, the water current is se devices is of high significance primarily because of fastest at the centre, but in a river this may vary de- two opposing reasons. First, there is the potential of pending of the bottom. Therefore, the water velocity increasing the power capacity, and hence reduce the has a localized and site-specific profile, and where the cost of energy. On the other hand, there may be a lack rotor is located dictates the amount of energy that can of confidence concerning their survivability and de- be produced. [3] Second, in a river there are compe- sign [3]. Figure 2.1.2.1 illustrates some of the types. ting users of the water stream. This could be boats, fishing vessels, bridges, etc., and these might reduce the effective usable area for a turbine installation [6]. There could also be varying types of suspended par- ticles and materials like fish, rock, ice, etc. in the river [4]. Properly placing a hydrokinetic turbine requires an understanding of what influences the kinetic energy or velocity of the water at any point in the river. This can be studied further in the report Siting Considera- tions for Kinetic (In-Stream) Hydro Turbines made Figure 2.1.2.1: Examples of ducts/diffusers [4] by ABS Alaskan, Inc [5].

ZERO - Small-scale Water Current Turbines for River Applications 3 Companies and technologies Table 3.1 gives a summary of the concepts that are To find the companies that are established and emer- in a commercial or pre-commercial stage today. Pre- ging within this field, a web-based search was perfor- commercial means that it has done a demonstration med. Earlier written reports dealing with this subject of a commercial size unit. Commercial means that were also reviewed. Especially a report about the there are units commercially available. No device on technical status in 2006 made by Verdant Power [6] is a laboratory or prototype stage is considered. used to list the present companies.

Companies and technology summary table

WCT Stage of Min/Max Min/Max No. of Ducted Unit Turbine Axis of Blade di- Anchor Company Device Devel- Depth Speed Turbines or Un- Power Type Rotation ameter System Name opment (m) (m/s) per Unit ducted Output

Thropton 0.5/ Water Axis flow 4.0, 3.4, Up to Energy Com- depends Un- Pontoon, Current propel- Min 0.75 Horiz 2.8, 2.2, One 2kW at Services mercial on ducted boat Turbine ler 1.8 m 240v (UK) diameter

Free- Alternative MIn 0.6 0.5/ Cus- stream 1.25, 1.5, Hydro So- Cross- Com- for high depends Un- tomer Up to Darrieus Vert 2.5, 3.0 One lutions Ltd axis mercial speed on ducted deter- 2-3kW Water m (Canada) stream diameter mined Turbine

Sub- Weight- Energy 1-5kW merged Cross- Com- 0.5/ No data ed base Alliance Min 3 Horiz One Ducted (and >10 Hydro axis mercial no limit found and (Russia) kW) Unit cabled

Floating EnCur- New Min 0.5/3 buoy 5kW rent Cross- Com- Un- Energy MIn 2.5 for max Vert 1.52 m One with (and > Hydro axis mercial ducted (Canada) power cables to 10kW) Turbine anchors

Tidal Depends Darrieus, Moored Energy Pre-com- No data No data on veloc- TBD Cross- Vert 1.2 to 2.4 One Ducted to the Pty. Ltd. mercial found found ity and axis ground (Australia) size

Lucid Helical Vert: no Up to Gorlov One or Energy Darrieus Com- limit. 0.6/no No data Un- 20kW, Helical Either more Various Technolo- Cross- mercial Horiz.: limit found ducted depends Turbine sections gies (USA) axis ~1.1 on size

Floating Unde- Seabell Int. Dual, buoy Com- 0.5/no 0.6/no No data fiend Co., Ltd. STREAM Cross- Vert Two Ducted with mercial limit limit found (small- (Japan) axis cables to scale) anchors

Eclectic Axial 1/5 (1.8 8 amps Com- 0.5/no Un- Pontoon, Energy DuoGen flow pro- knots/9 Horiz 0.31 m One at 6 mercial limit ducted boat Ltd. (UK) peller knots) knots

Table 3.1: Companies and technology summary table NOTE: Most of the information presnted is gathered from the cpmåany’s own websites or published litterature without thrid party confirmation and should be evaluated in light of each design-developer’s experience and track record of date.

ZERO - Small-scale Water Current Turbines for River Applications 3.2 Companies and concepts

As may be read from table 3.1, there are several companies with viable concepts within this field. In the following chapter, the companies and a short outline of their concepts will be presented.

3.2.1 Thropton Energy Services (UK) Thropton Energy Services provide a complete range of services relevant to water current turbines from resource assessment to design and supply local manufacture. The company claims to have twenty years of experience in this field and have worked in UK, Sudan, Somalia, Egypt and Peru.

The company is the designer and manufacturer of the Garman turbine, which can be used for both water pumping and electricity generation. The turbine is axial and can be thought of as an underwater wind- mill which floats on a river or canal with the rotor completely submerged. It is moored in free stream to a post on one bank, making installation simple and cheap and minimising obstruction to river traffic. The propeller fan style turbine, available in diameters of 4.0, 3.4, 2.8, 2.2, and 1.8m drives an above-water generator.

The turbines are stand-alone units and have a maxi- mum power output of about 2kW. To keep the capital cost down, Thropton has designed the turbine so that it can be locally manufactured. Garman turbines are being manufactured in Sudan, where they are used for pumping irrigation and drinking water from the Nile and for electricity generation. The systems are said to be easily deployed without heavy equipment, and thus they are suitable for use in developing countries.

Minimum site requirements are a water current speed of at least 0.5m/s and a depth of 1.75m or more. [1]

Price per unit: Available on request

Contact information: Dr. B Sexon Thropton Energy Services Physic Lane, Thropton, Northumberland NE65 7HU,United Kingdom Tel: +44 1669 621288 E-mail: [email protected] Web page: http://www.throptonenergy.co.uk/

ZERO - Small-scale Water Current Turbines for River Applications 3.2.2 Alternative Hydro Solutions Ltd. (Canada) Alternative Hydro Solutions Ltd. has taken the Dar- rieus concepts and modified them to be more suitable for smaller rivers.

These small Darrieus turbines are, according to Al- ternative Hydro Solutions Ltd., constructed of high quality and durable materials. The turbine blades are made of aluminium with a solid cross-section in order to provide the required strength.

A number of electrical options are available depending on site requirements. These include a permanent magnet D.C. generator and a brushless alterna- tor. The turbine is available in several diameters: 1.25 m, 1.5m, 2.5 m, 3.0 m, and 6.0 m, each available in custom lengths. [6]

The water flow speed that is generally accepted as the minimum for power production is 0.8 m/s [7]. The efficiency curves illustrated below indicates the power versus velocity for various combinations of diameter and height.

The company make several different sizes based on the customer needs. The 2m height by 3m diameter one has a cross sectional area of 6m^2 and will produce 750W at 1m/s. The turbine itself goes into a 2.5m by 2.5m by 0.5m box and assembles at site. It weighs about 200kg. If there was a known place some assembly could be done closer to site but this would only be of the bearing and shaft/ generator section.

Price per unit: Depends on size.750 W (at 1m/s): cen $ 5000

Contact information: Alternative Hydro Solutions Ltd., Suite 421, 323 Richmond Street East, Toronto, Ontario, M5A 4S7, Canada Tel: 416 368 5813 E-mail: [email protected] Web page:http://www.althydrosolutions.com/

10 ZERO - Small-scale Water Current Turbines for River Applications 3.2.3 Energy Alliance (Russia) Energy Alliance has a concept based on a in-plane, cross-axis turbine. A stream-flow having sufficient width, depth and velocities of about 3 m/s can be used for installation of the submerged turbine. At higher velocity, higher output can be obtained with the hydro-unit overall dimensions unchanged.

The turbine is housed in a duct that allows the system to be placed in a swift flowing river without the use of a dam. The units are expected to stay reliably secured by hydraulic and hydrodynamic forces. The submerged units can be operated year round, including the case when they are installed in the rivers with incom- plete freezing of the river bed. The Energy Alliance plans to produce two versions of submerged hydro- units - portable units with outputs from 1 to 5 kW and stationary units with outputs from 10 kW to 225kW. The portable submerged hydro-units are intended for generation of 12V and 28V direct current, depending on the parameters of stream flow and generator type. [8] The turbines are currently in production [6].

Price per unit: Tentative price for up to 16kW: 12800 USD (Jan 2010)

Contact information: Energy Alliance, 198095, St. Petersburg, Obvodny Kanal 122, Russia Tel: 259-91-27 Fax: 113-02-07 E-mail: [email protected] Web page: http://informal.ru/www.energy-alliance.spb.ru/sin- ke.htm

ZERO - Small-scale Water Current Turbines for River Applications 11 3.2.4 New Energy Corporation Inc. (Canada) New Energy Corporation Inc., with support from Natural Resources Canada and the CANMET Energy Technology Centre, have developed a series of turbine/generator sets that produce between 5 kW and 25 kW of power and are supposed to be used in rivers, irrigation canals, industrial outflows, and tidal estua- ries. The EnCurrent generator is based on the vertical axis hydro turbine. It employs hydrofoils mounted parallel to a vertical shaft which drives a permanent magnet generator, with all electrical equipment mounted above the water surface.[9]

According to the website of the company, the 5 kW EnCurrent Power Generation System generates enough electricity to power two to five average ho- mes on a continuous basis and is available in a stan- dalone or grid connected configuration. The system is available in three models: A high velocity model (5 kW power output at 3 m/s), low velocity model (5 kW power output at 2.4 m/s) and restricted flow model. The restricted flow model uses a five bladed turbine which increases the resistance in the turbine. It is used in locations where the majority of the water in the channel flows through the turbine and where the increased resistance causes water to accumulate behind the turbine. [10]

ABS Alaskan delivers the EnCurrent systems. Every EnCurrent turbine is sold as a complete “water to wire” package, including appropriate inverters for the system type [11]. Overall system mass for a 5kW turbine is 340-360 kg and the height is 2.25 m. Shipping charges will be clarified by request, depending on how many devices that are ordered and where they are to be delivered. The economic payback for the system is promised to be as little as two years.

Price per unit: For a 5kW turbine: 28000 USD (Jan 2010)

Contact information: New Energy Corporation Inc. 3553 - 31 Street NW, Suite 473 Calgary, Alberta, T2L 2K7, Canada Tel: (403) 260-5240 Email: [email protected] Webpage: http://www.newenergycorp.ca

Main supplier: Abs Alaskan, Inc: www.absAK.com Technical Product Questions: [email protected] General Sales Questions: [email protected] Shipping Questions: [email protected]

12 ZERO - Small-scale Water Current Turbines for River Applications 3.2.5 Seabell International Co., Ltd. (Japan) According to Seabell International Co website, The STREAM is the world’s first invention of a «Dual axis turbine» (flat type, dual vertical axis), with an opposi- te rotation accelerating gear system and a system that reduces friction loss.

The current speed accelerates by taking in a large mass of natural non-head water current into the axel chamber. The smooth inflow/outflow design is supposed to minimize hydraulic head loss (friction) and capture energy efficiently.

The generator is mounted above the waterline, and this reduces manufacturing and maintenance costs. It is always suspended on the water surface, where the fastest current speed is, thus the largest concentration of energy exists in rivers and water ducts.

Employing dual axis structure taking into account flow behaviour of ducts, where the largest energy always exists at the centre. [12]

Price per unit: Available on request

Contact information: Seabell International Co Mansan Building 2-8-11 Higashi-kanda, Chiyoda-ku, Tokyo, Japan 101-0031 Tel: +81-35822-2275 Fax: +81-35822-2274 E-mail: [email protected] Web page: http://www.seabell-i.com/e/

ZERO - Small-scale Water Current Turbines for River Applications 13 3.2.6 Lucid Energy Technologies (US) Until 2007, GCK was the licensee of the Gorlov He- lical Turbine (GHT) patents and technology. Then GCK Technology entered into a Joint Venture Agre- ement in March of 2007 to form Lucid Energy Tech- nologies. All business relating to the GHT Techno- logy is now being conducted through Lucid Seabell International Co [13].

GHT is a cross-axis turbine consisting of one or more long helical blades that run along an imaginary cylin- drical surface of rotation like a screw thread. The design made by Alexander M. Gorlov developed at the North-eastern University, Boston, U.S.A has gained significant attention for both river and tidal applications [4]. Gorlov and co-workers in the United States tested models of the cross-flow turbine with helical blades and claim that its performance is superior to a conventional Darrieus cross flow turbine. The picture to the left shows two different examples of the concept.

The generated capacity is said to be proportional to the number of modules. In its vertical orientation the generator and gearing can easily be positioned above water. It starts producing power at approximately 0.60 m/s, according to studies done in 2004.[6] According to Lucid, the Airfoil-shaped blades move at twice the speed of the current and the components can be assembled and replaced on-site. The aluminium construction is lightweight, rustproof, and re- cyclable.[13

Price per unit: Available on request

Contact information: Lucid Energy Technologies 118 East Washington Street, Suite 2 Goshen, IN 46528, US Tel: (574) 537-7300 E-mail: Unknown Web page: http://www.lucidenergy.com

14 ZERO - Small-scale Water Current Turbines for River Applications 3.2.7 Tidal Energy Pty. Ltd. (Australia) Tidal Energy is a company that was formed in 1998. Despite the fact that the scope of this report was to focus on applications in free-flowing rivers and not on tidal energy, the concept is considered because of the possible use in tidal streams like the Amazon River. According to the firm, flows around 2 m/s are ideal for electricity production with this turbine. The concept is pre-commercial, but Tidal Energy is offering demonstration turbines for sale or lease.[14]

Price per unit: Capacity at 0.77-6.16 kW (1-2m/s): 35 000 AU$ (Jan 2010)

Contact information: Tidal Energy Pty. Ltd. Bill Maywes, Australia SKYPE. bmeywes (preferred) Tel: +61 401 052 522. E-mail: [email protected] Web page: http://www.tidalenergy.net.au

ZERO - Small-scale Water Current Turbines for River Applications 15 3.2.8 Eclectic Energy Ltd. (UK) The DuoGen is a combined water and wind mill. It is made to produce electricity to run most of the on- board equipment when sailing a yacht. Although this kind of technology is not in the scope of this report, it is considered because of the possibility of using it in a river or a stream.

The picture to the left shows when DuoGen is in its water mode. The DuoGen water mode is said to ope- rate in a controlled fashion within the top 500mm of the water. This, coupled with the design of the three- bladed impeller, ensures that drag is minimised. [19] Several wind/water combinations are available on the market, but Eclectic Energy claim that they tend to be adaptations of single purpose machines and are cha- racterised by being problematic to deploy and reco- ver. DuoGen is supposed to be easy and efficient.

Price per unit: Short Tower (1.3 metre): £1699.00 (including VAT) Long Tower (1.6 metre): £1749.00 (including VAT) Extra Long Tower (1.85 metre): £1849.00 (including VAT) (Jan 2010)

Contact information: Eclectic Energy Ltd. Edwinstowe House High Street, Edwinstowe, Nottinghamshire, NG21 9PR , United Kingdom Tel: +44 1623 827829 E-mail: [email protected] Web page: http://www.eclectic-energy.co.uk/

16 ZERO - Small-scale Water Current Turbines for River Applications 4 Research and experiences

The technology of small-scale hydro power is still in the stage of development and the possibilities are not yet fully explored. Small-scale hydro power has a growing interest around the world, and different concepts have been tried out with various outcomes.

As mentioned, the company Thropton Energy -Ser vice has twenty years of experience in the field of hydrokinetic turbines and have worked in UK, Sudan, helical turbine used at the station. This turbine was Somalia, Egypt and Peru. They claim to have success built locally by a mechanic and a welder. The only in implementing their technology in remote areas outside components were the helical turbine blades and have done a case study where a farmer in Sudan themselves.[18] If this technology proves viable in the got irrigation water for his 12 acre of land relying on pilot phase, the organization expect that hundreds of their Garman turbine. The turbine replaced an earlier small, tide-powered generating stations will be built diesel engine powered system which required conti- near the mouth of the Amazon and elsewhere along nuous supplies of fuel and oil which can be difficult the adjacent Atlantic coast. The organization claims to obtain in isolated areas. Eighteen months after the that because the technology is accessible, affordable, installation, the farm was visited by Thropton Energy and inherently small-scale, these stations can be built, Services staff. The turbine was working to the farmer’s owned, and operated by hundreds of rural residents. satisfaction and had at that time run for more than The people could use the energy for themselves and 11,000 hours without breakdown and without any also offer battery charging service to their neighbours. spare part being fitted. [21] The project started in 2006. The author has not been successful in providing a temporarily status report. At the web site of New Energy Corporation, a case study of a 5 kW EnCurrent Power Generation System is Information on several designs with horizontal and presented [22]. Electricity from the turbine started to vertical axis rotors that were tested in the Amazon flow into the micro-grid in Ruby, Alaska on August, regions of Brazil could be found in [24]. The report 2008. Ruby is a community of approximately 200 re- summarizes the status of the use of small-scale hy- sidents located on the Yukon River in central Alaska. drokinetic technology in the the region up to 2003. Electricity generation for the community is currently According to the report, the most successful expe- provided by diesel local tank farm, but the area has a riences in the Brazilian area were done by a research large potential for hydrokinetic industry due to the group from the Department of Mechanical Engine- high energy costs and abundant river and tidal re- ering at the University of Brasilia. Several experiences sources. The system at Ruby has validated the concept with diverse prototypes of vertical and axial turbines of installing hydrokinetic turbines and producing po- were performed, as is further discussed in the paper wer to micro-grids in Alaska. It is now being moni- Hydrokinetic Turbine for Isolated Villages [25]. The tored for performance, grid integration, fisheries and article conclude with that the hydrokinetic turbines navigation issues. These findings will then be used to presented in the paper are functioning, produce sta- further improve and perfect the hydrokinetic system. ble electrical energy at 220 volts and permits the use [22] of domestic equipment. The developed technology proved to be robust and suitable for the extremely Another demonstration, with a Gorlov-type turbine severe conditions of the remote and isolated villages, was done in the Amazon, by a non-profit organiza- since it had been functioning uninterruptedly for se- tion called IPAM, a Brazilian NGO. For the prototype ven years. The hydrokinetic power plant that was tes- at this site, it was expected that the energy produced ted typically provided up to 2kW of electric power, would be sufficient to meet the basic needs of 10 hou- depending on river characteristics. It was considered seholds, at World Bank standards for rural electrifica- a reliable alternative for the electrification of isolated tion using solar energy. [18] households and communities.

In order to capture the energy of the tides near the Research results on inclined axis turbines have been mouth of the Amazon River in Brazil, a prototype reported in the articles [26] and [27]. In these works, station was built, with characteristics adapted for the feasibility of utilizing river energy in Bangladesh small-scale generation of electricity in a rural area. was studied, and conclusions were drawn in favour of The photograph shows a six-blade version of the

ZERO - Small-scale Water Current Turbines for River Applications 17 such technologies. The effects of varying blade pitch electrical energy in comparison to other small-scale and shaft inclination angle were also studied and the renewable technologies. Also, the peak energy season average mechanical system efficiency was reported to is during the winter months when large quantities of be 30%[15]. electricity are required [2]. No reservoir is required and it is considered as a cost effective energy solution The latter report, along with other research done in because of the low investment costs and maintenance this field, is listed in the article River current energy fees. Water current turbines are therefore said to be conversion systems: Progress, prospects and challen- an efficient and environmentally friendly technology ges from 2007 [15]. The article may serve as a litera- for small-scale energy production. However, there are ture survey or technology review, and may provide certain disadvantages that should be considered be- better understanding of the issues and research inte- fore constructing a small hydro power system. rests in the field of water current technology. Some of the designs mentioned are patented technologies First of all, in many locations stream size will fluctu- meant for large scale energy conversion, but much of ate seasonally. During the summer months there will the knowledge can also be used for small-scaled tech- likely be less flow and therefore less power output. nology. Advanced planning and research are needed to en- sure that adequate energy requirements are met [2]. When doing literature search for this report, research Another issue is that the power efficiency strongly -de results, experiments and case studies with well docu- pends on the location of the turbine. Suitable site cha- mented controls were hard to find. A website called racteristics are required, and their localization may be International Small Hydro is a new site that is suppo- complicated and time consuming. sed to provide data for potential and developed small- scale hydro sites [17]. The site also describes the sta- The ecological impact of small-scale hydro is mini- ges of planning that are required to determine if a site mal, however the locally environmental effects must is technically and economically feasible. This can be a be taken into consideration before construction be- good source of information for future projects. gins [2]. Factors such as possible down-stream flow alterations and adversities on aquatic plants and ani- mals should be brought into light [15]. 5 Discussion These types of developments can bring about environmental and socio-economic benefits through Unlike conventional hydro and tidal barrage instal- integrated design, multipurpose planning and com- lations, water current turbines in open flow can ge- munity involvement. [2] The turbines can replace nerate power from flowing water with almost zero earlier diesel engine powered systems which requires environmental impact, over a much wider range of continuous supplies of fuel and oil. Due to the isola- sites than those available for conventional tidal power tion of certain areas, obtaining fuel supplies is often a generation. constant problem. The turbines could potentially provide several services such as water pumping for sto- Small-scale hydropower is especially attractive as an rage, livestock, human consumption, small industry, alternative to highly polluting and costly diesel gene- and irrigation. In such applications, water pumps ration that provides electric energy in remote commu- could be employed instead of electrical generators, to nities across the world. Since many remote commu- facilitate direct mechanical energy conversion. [15] nities are situated near moving water these turbines If the use of this technology in rural areas is to be a represent a promising source of clean power. success however, the turbines must be easy to use and the quality must be reliable. Most of the components, such as blade, generator, power converter, etc., needed for designing a turbine system are mostly readily available. Therefore, product development cycle, cost and level of technical sophistication are expected to be low. [15]

There are several advantages with this kind of technology compared to other small-scale power devices. As mentioned, it only takes a small amount of flow to generate electricity. It is reliable in the sense of that the water stream produces a continuous supply of

18 ZERO - Small-scale Water Current Turbines for River Applications 6 References cPath/33_89_90/products_id/1098 [1] Thropton Energy, Physic Lane, Thropton, Northumberland NE65 7HU, United Kingdom, [12] Seabell International Co., Ltd, January 2010 January 2010. http://www.seabell-i.com/e/ http://www.throptonenergy.co.uk/ [13] Lucid Energy Technologies, January 2010 [2] Alternative Energy, January 2010 http://www.lucidenergy.com/ http://www.alternative-energy-news.info/ micro%20hydro-power-pros-and-cons/ [14] Tidal Energy Pty. Ltd., January 2010 http://www.tidalenergy.net.au/?D=1 [3] M.J. Khan, G. Bhuyan, M.T. Iqbal and J.E. Quai- coe; Hydrokinetic energy conversion systems and [15] M.J. Khan, M.T. Iqbal and J.E. Quaicoe, River assessment of horizontal and vertical axis turbines current energy conversion systems: Progress, pro- for river and tidal applications: A technology status spects and challenges, Renewable and Sustainable review, Applied Energy, October 2009, Pages 1823- Energy Reviews, October 2008, Pages 2177-2193 1835 (ScienceDirect) (ScienceDirect)

[4] Hydrovolts, January 2010 [16] G. Ranjitkar, J. Huang and T. Tung, Application http://www.hydrovolts.com/MainPages/ of Micro-hydropower Technology for Remote Re- Hydrokinetic%20Turbines.htm gions, Hydraulic Energy Program, CANMET Energy Technology Centre, Natural Resources Canada, 2006 [5] ABS Alaskan Inc. report, January 2010 (IEEE: Authorized licensed use limited to: Norges Siting Considerations for kinetic (In-Stream) Hydro Teknisk-Naturvitenskapelige Universitet. Downloa- Turbines ded on January 12, 2010 at 06:58 from IEEE Xplore. http://www.absak.com/tech/EnCurrentSiting.pdf Restrictions apply.)

[6] Verdant Power, June 2006 [17] International Small Hydro Atlas, January 2010 Technology Evaluation of Existing and Emerging http://www.small-hydro.com/index. Technologies cfm?fuseaction=welcome.home - Water Current Turbines for River Applications http://www.hydrovolts.com/Refs/Verdant%20River% [18] S. Anderson, The Tide Energy Project Near 20Turbines%20report.pdf the Mouth of the Amazon Capturing Energy from River, Tide, and Ocean Currents - an Example of [7] Alternative Hydro Solutions Ltd., Suite 421, 323 Efficient, Practical Technology Using the Helical Richmond Street East, Toronto, Ontario, M5A 4S7, Turbine, May 2006 tel: 416.368.5813, January 2010. http://www.globalcoral.org/Capturing%20Energy%2 http://www.althydrosolutions.com/ 0from%20River,%20Tide,%20and%20Ocean%20Cu rrents.htm [8] Energy Alliance, January 2010 http://informal.ru/www.energy-alliance.spb.ru/sin- [19] DuoGen, January 2010 ke.htm http://www.duogen.co.uk/

[9] V. Ginter and C. Bear, New Energy Corporation [20] Eclectic Energy Ltd., January 2010 Inc., http://www.eclectic-energy.co.uk/ Development and Application of a Water Current Turbine, 2009 [21] Thropton Energy, Supply of irrigation water for http://www.newenergycorp.ca/LinkClick.aspx?filetic 12 acre date, January 2010 ket=5%2btQK3cID%2fY%3d&tabid=84&mid=471 http://www.throptonenergy.co.uk/casestudy.html

[10] New Energy Corporation, January 2010 [22] New Energy Corporation, Casestudy in http://www.newenergycorp.ca/Products/ Alaska, 2008 http://www.newenergycorp.ca/Por- PowerGeneration/5kWPowerGenerationSystem/ta- tals/0/documents/case_studies/Ruby.pdf bid/69/Default.aspx [23] GCK Technology, January 2010 [11] ABS Alaskan, January 2010 http://www.gcktechnology.com/GCK/pg2.html http://www.absak.com/catalog/product_info.php/

ZERO - Small-scale Water Current Turbines for River Applications 19 [24] G. L. Tiago Fo, The state of art of Hydrokinetic power in Brazil International Small Hydro Technologies, Buffalo, NY, USA, pre-conference Workshop, 2003 www.small-hydro.com/view/library/.../ Hidrocinética%206%20tra.doc

[25] R. H. Els, C. Campos, L. F. Balduino, A. M. Henriques, Hydrokinetic Turbine for Isolated Vil- lages, in X Encontro Latino Americano e do Caribe em Pequenos Aproveitamentos Hidroenergéticos, Poços de Cldas, Minas Gerais, Department of Me- chanical Engineering - University of Brasilia, May 2003, p- 298-272. http://www.cerpch.unifei.edu.br/Adm/artigos/a10e4 e0f6494ae3e6ab116b6d291d151.pdf

[26] A.K.M. Sadrul Islam, N.H. Al-Mamun, M.Q. Islam and D.G. Infield, Energy from river current for small scale electricity generation in Bangladesh, Proceedings of the renewable energy in maritime island climates, Solar Energy Society, UK, 2001.

[27] Al-Mamun NH. Utilization of river current for small scale electricity generation in Bangladesh. Master’s thesis, Department of Mechanical Engine- ering, BUET, Dhaka, July 2001

20 ZERO - Small-scale Water Current Turbines for River Applications ZERO - Small-scale Water Current Turbines for River Applications 21 22 ZERO - Small-scale Water Current Turbines for River Applications www.zero.no